1. Field of the Invention
This invention relates to a process for the copolymerization of a diene, such as butadiene, with an alpha-olefin, such as propylene using a catalyst comprising a titanium or vanadium halide, an aluminum trialkyl and carbon disulfide to give copolymers having a substantial proportion of propylene or other alpha-olefin therein.
2. Related Prior Art
The copolymerization of propylene with conjugated dienes has been reported in several instances. However, the methods reported for effecting such copolymerization have various disadvantages.
For example, British Pat. No. 1,108,630 shows the use of a catalyst system comprising TiCl.sub.4, aluminumtrialkyl and iodine.
French Pat. No. 2,047,646 shows the use of a catalyst system comprising TiX.sub.4 wherein X is Cl, Br or I, AlR.sub.3 wherein R is alkyl, aryl or cycloalkyl, and a compound containing a carbonyl group. Preferred carbonyl compounds as illustrated in the examples are benzophenone, diisobutyl aldehyde, benzoyl chloride, isobutyric acid, benzoic acid, monochloroacetic acid, maleic anhydride, diethyl malonate, diethyl acetate, acetone, benzaldehyde, acetic anhydride, etc. Temperatures of -30.degree.C. to -40.degree.C. are apparently preferred since all of the 34 working examples are conducted at these temperatures with the exception of one at -15.degree.C. and one at -55.degree.C.
The low temperature polymerization in these prior art systems are impractical for industrial purposes because of the added expense and slow polymerization rates.